Ground Based Microwave Radiometric Technique in Remote Sensing

As an important tool of atmospheric remote sensing, microwave radiome- ters are used for temperature profiling and vapor and liquid column measurements. In addition, ice water path can be retrieved using radiometer observations. In this review, the potential of radiometers is demonstrated by comparison with radiosonde data and observations using Global Positioning Systems (GPS). Performance of various mathematical retrieval methods for water vapor and cloud liquid water profiles using microwave radiometer measurements are compared. These include regression methods, Newton iteration and neural networking. A specific case of temperature inversion near the ground and its retrieval by Philips-Twomay method is discussed. Microwave Radiometers can be either ground based or satellite borne. At present Advanced Microwave Sounding Units (AMSUs) are used on NOAA's TIROS (Television Infrared observa- tion Satellite) satellites to provide temperature and water vapor profiles. They have low spatial and temporal resolution but large spatial coverage. So at a specific location, if we require vertical temperature distribution, ground based radiometer will be useful. The large emission measured